The purpose of the immunodeficient mouse core facility is to serve the investigators in this program project by providing them with access to biological models to test the tumorigenicity of prostate carcinoma in vivo. The severe combined immune-defcient (SCID) mouse human tumor xenograft model will be the predominant model employed in these studies but other animal models such as the athymic nude mouse model may also be utilized. The SCID mouse xenograft models test tumor growth, adhesiveness, penetration, local spread and distant metastases. The specific measurable end points are both qualitative and quantitative. Qualitative assessments include gross anatomic as well as histologic and phenotypic descriptions of the immunotopography of human prostate xenografts. Quantitative assessment includes tumor xenograft size, number, depth of invasion, and animal survival data. Models have been developed utilizing both ectopic as well as orthotopic injections of human prostate cell lines, This core will support the projects in the following manner: 1) Provide the technical expertise to perform the SCID mouse-human tumor xenograft experiments. 2) Assist with the design and interpretation of experiments utilizing SCID mouse models of human prostate tumor growth and metastasis. 3) Provide fixed, frozen, and fresh tissue from the SCID mouse human xenografts for analysis as described in projects 0001, 0002 and 0005.